Mechanical seals are used in a wide variety of industrial applications. Often, the sealing applications necessitate the use of a gas barrier system. This means that the seal faces must run “dry”, as herewith described.
As recognized by one skilled in the art, typically, mechanical seal faces utilize a fluid film. This fluid film is positioned between the pair of seal faces and acts to lubricate and cool the seal faces during dynamic operation.
If a pair of seal faces is utilized to seal a marginal lubrication fluid and/or a gas, for example nitrogen, the fluid film may also be considered to be a gas. Such a fluid film may provide very little seal face lubrication, which may result in a high amount of heat generation. Such heat may be dissipated into the respective mechanical seal faces. There are many factors, which will increase the heat generated between the pair of mechanical seal faces. Pressure and counter rotational surface speed are two of such factors.
Heat between mechanical seal faces may be undesirable for at least the following reasons:
Firstly, some environments contain gases which can auto ignite should the gas come into contact with heated surfaces. In the case of a mechanical seal, seal faces running at elevated temperatures may increase the possibility of a problem and/or may reduce the possibility of their wide application. The European directive, which describes such environments, is discussed in 94/9/EC. Further information is contained in DIN EN1127-1:1997, prEN13463-1:2001, prEN13463-5:2000 and prEN13463-6:2002.
Secondly, this condition may also increase seal face deterioration and reduce seal face life.
It is deemed advantageous if a seal design is created which reduces the heat transferred into a seal face, which is operating in poor fluid film conditions.